The purpose of this project is to determine whether DNA sequence differences in the promoter regions of the several human globin genes are relevant to their developmental regulation. Our first objective is to obtain a functional profile of the human Gamma globin gene promoter. "Mutant" promoters are created in vitro by deletion or by the "linker scanning" method and the function of these mutant genes is tested in monkey kidney cells using plasmid expression vectors. We have demonstrated that the Gamma globin gene promoter requires an independent remote enhancer sequence for function in monkey kidney cells. Deletion mutants down to 130 bp of the start site of transcription continue to function although a deletion mutant to 55 bp is non-functional. A library of linker scanning mutants in which the 10 bp Bam HI linker replaces a corresponding segment of the promoter region, is being constructed and will be studied in monkey kidney cells, hematopoietic cell lines, and possibly in normal human bone marrow cells by various gene transfer techniques.